Leagally this should get him off. This brings back bad memories of my military days having to administer piss tests when someone got serously hurt to insure drugs weren't involved. I've also seen were tests came up invalid due to the chain of custody was broken.
If he doesn't get off it explains the CSAC, but it could drag on equal a year suspension with no fines. Not sure but don't they hold some of his pay for that night? So in the end he may win but still lost!